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Cell Phone-based Optometry Solution

The Inverse of Shack-Hartmann

Vitor Pamplonaeyenetra.com

Andres Rueda

Thermometer for vision

Collaboration with: Ankit Mohan , Manuel M. Oliveira, Ramesh Raskar

Collaboration with: Ankit Mohan , Manuel M. Oliveira, Ramesh Raskar

Thermometer for vision

6.5 Billion

people

4.5B have a

cell phone

2B have

refractive errors

0.6B have URE

Shack-Hartmann Wavefront Sensor

Expensive; Bulky, Requires trained professionals

Wavefront aberrometer

6


Laser

Sensor MicrolensArray

Planar Wavefront

Spot Diagram

Laser

Sensor

8

Displacement = Local Slope

of the Wavefront

Spot Diagram


NETRA = Inverse of Shack-Hartmann

9

Spot Diagram on LCD

Cell Phone Display

Eye Piece

10

Spot Diagram on LCD

Inverse of Shack-HartmannUser interactively creates the Spot Diagram

Displace 25 points but 3 parameters

11

Spot Diagram on LCD

Inverse of Shack-HartmannUser interactively creates the Spot Diagram

Displace 25 points but 3 parameters

Eye

Relaxed Eye with Myopia

Blurred point

Red pointat infinity

perfect vision

myopia

hyperopia

~10cminfinity

Focusing Range

12

Eye


Distinctimage points

perfect vision

myopia

hyperopia

~10cminfinity

Focusing Range

Pinholes

13

Red pointat infinity

Scheiner’s Principle

Eye


Virtual red pointat infinity

perfect vision

myopia

hyperopia

~10cminfinity

Focusing Range

14

A

B


Display


A

B

perfect vision

myopia

hyperopia

~10cminfinity

Focusing Range

Virtual red pointat finite distance

Move spots towards each

other

Display

Eye

15


B

A

Points overlap


Display

perfect vision

myopia

hyperopia

~10cminfinity

Focusing Range

Eye



other

16

B

A

Points overlap


Display

perfect vision

myopia

hyperopia

~10cminfinity

Focusing Range

Eye



other

17

d

Points overlap


perfect vision

myopia

hyperopia

~10cminfinity

Focusing Range

Eye

18

d

d

1

Point at infinity

Interactive Method

20

Interactive Method

21

Interactive Method

22

Interactive Method

23

Interactive Method

Farthest Focal Point(myopia, hyperopia, astigmatism) 24

Limitations

• Children

• Ability to align lines

• Resolution is a function of the display DPI

– Samsung Behold II – 160 DPI – 0.35D

– Google Nexus One – 250 DPI – 0.2D

– Apple iPhone 4G – 326 DPI – 0.14D

25

Why Now?

0.35um

Confidential 27

NETRA Prototypes Worldwide29 partners in 14 countries.

Clinical Testing Partners

NETRA Team at LVPEI, India

Tufts U. (Boston) NETRA vs Manifest Refraction

-5.00

-4.00

-3.00

-2.00

-1.00

0.00

1.00

2.00

3.00

4.00

5.00

-5.00 -3.00 -1.00 1.00 3.00 5.00

Net

ra (D

)

Retinoscopy (D)

13 adults

-7.00

-5.00

-3.00

-1.00

1.00

3.00

5.00

7.00

-7.00 -2.00 3.00

Net

ra (D

)

Retinoscopy (D)

29 adults

LVPEI (India)NETRA vs Retinoscopy

Validation: Side by Side Trials

Preventable Blindness

WHO 2004

Unique, quantitative lens mapping

CATRA: Quantitative Cataract Maps

with: Erick Passos, Jan Zizka, Everett Lawson, Esteban Clua , Manuel M. Oliveira, Ramesh Raskar

Testing the Presence of Cataracts

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Blin

kin

g p

atte

rns

on

Scr

ee

n

Cell Phone Display

Pinhole

Lens

36 years old female with Posterior Sub-Capsular (10%)

CATRA’s Opacity MapSlit-lamp

Retro-illumination

For the Future

• Ophthalmology for Masses– >.5 billion URE. > 2.5 billion RE. -> Devices for all

• Quality of phones (resolution) will increase exponentially

• New features (recently cataracts, next Retinal NETRA)

• Smart phones will take over the market in developing world countries like India in next 5 years.

• Hardware store

NETRAhttp://eyenetra.com

Vitor Pamplona

Photography in 1960s

Illana Tamir

Roboppy

Today, cameras are everywhere

Photo: Derek K. Miller

Photo: Tyler

Photo: John Kannenberg

Corneal TopographerWavefront Aberrometer

Phoropter

Optometry Today

Snellen chartTrial set of lenses Lasers

“point-and-shoot” optometry

Traditional User Driven

Mass-use Devices Scientific Instruments

Phoropter

Snellen chart

Trial lenses

Reading Charts

• Accuracy– Sharpness Estimation is subjective

– Brightness affects results

– Pupil size variation and DoF

• Cost– Trial Lens Set > $150

– Bulky

EHR

DeliveryDiagnosticEyecare

Providers

New Ecosystem

Asynchronous

Medical IT Systems

Retinoscope w/

Lenses

Auto-refracto-

meter

Chart with

Lenses

In-Focus: Focometer Optiopia

Solo-health: EyeSite

NETRA

Technology Shining Light plus lenses

FundusCamera

Moving lenses + target

Moving lenses + target

Reading chart on monitor

Cellphone+ eyepiece

Cost to buy $2,000* ~$10,000 ~$100 ~$495 ~$200 -- $30

Cost per test ~$36 ~$36 ~$5 -- -- -- ~$1

Data capture No Comp. No No No Comp. Phone

Mobility 10Kg 2kg 1kg 10Kg

Human Eye

Human Eye

Cornea(~40D) Crystalline lens

(10~20D)

Retina

46

Human Eye

Human Eye

Cornea(~40D) Crystalline lens

(10~20D)

Retina

47

Accommodation

Infinity

Perfect Vision System

Human Eye

Infinity

Subject can focusat infinity

10cm

Normal Vision

48

Accommodation Range

Myopia (nearsightedness)

Infinity

Subject cannot focusat far distances

10cm

Normal Vision

Myopia

Wrong focal point

49

Accommodation Range

Infinity

Human Eye

Myopia Correction

Infinity

Subject can focusat infinity

10cm

Normal Vision

Myopia

Divergent Lens

Corrected Myopia

50

Accommodation Range

Infinity

Human Eye

Hyperopia (farsightedness)

Infinity 10cm

Normal Vision

Myopia

Hyperopia

Wrong focal point

51

Accommodation Range

Infinity

Human Eye

Hyperopia Correction

Infinity

Accommodation Range

10cm

Normal Vision

Myopia

Hyperopia

Convergent Lens

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Corrected Hyperopia

Infinity

Human Eye

Refractive Errors and Shifted Range

Perfect vision

Myopia

Hyperopia

10cmInfinity

Need to measure

54

1m 33cm Distance

Refractive Errors and Shifted Range

Perfect vision

Myopia

Hyperopia

10cmInfinity

55

-10D0D

Diopter = 1/Distance

-3D-1D

1m 33cm

+1D+3D

Distance

Diopter

Astigmatism: angle-dependent refractive error

http://www.elizabethpope.co.uk/eyeinfo/astigmatism.html 56

Refractive Power as a Function of Angle

59

Cylinder SphereAxis Cyl.Unknowns:

SCP )(sin(2

Astigmatism

Cross or points may never meet with a 1d search !60

Astigmatism

Lines reduce the problem to a 1d search61

Measuring the Accommodation Range

62

Perfect vision

~10cmInfinity

Myopia

Hyperopia

Step 1: Far limit Step 2: Near limit


63

Perfect vision

~10cmInfinity

Myopia

Hyperopia



64

Perfect vision

~10cmInfinity

Myopia

Hyperopia


Points overlap

A

B

Display

Virtual Point at the far limit

Relaxed Eye

65

Points overlap

A

B

Display

Accommodated Eye

66

Virtual pointgetting closer

Move points towardseach other

Subject Accommodates to fix the “blur”

Points overlap

A

B

Display

Accommodated Eye

67



Subject Accommodates to fix the “blur”

Points overlap

A

B

Display

Accommodated Eye

68



Subject cannot accommodate more than the previous point

Patterns for Alignment Task

Displayed

Subject view

Displayed

Subject view

69

Visual Cryptography

A B A B A B A B A B

A B A B A B A B A B

[NaorShamir94]

Patterns for Alignment Task

Displayed

Subject view

Displayed

Subject view

70

Visual Cryptography

A B A B A B A B

A B A B A B A B A B

A B

[NaorShamir94]

Summary of Interaction

Farthest Point(myopia, hyperopia, astigmatism)

Nearest Point(presbyopia)

Accommodation Range

71

3

Science

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